text: /* SPDX-License-Identifier: GPL-2.0 */
  #ifndef __LINUX_COMPILER_ATTRIBUTES_H
  #define __LINUX_COMPILER_ATTRIBUTES_H
  
  /*
   * The attributes in this file are unconditionally defined and they directly
   * map to compiler attribute(s), unless one of the compilers does not support
   * the attribute. In that case, __has_attribute is used to check for support
   * and the reason is stated in its comment ("Optional: ...").
   *
   * Any other "attributes" (i.e. those that depend on a configuration option,
   * on a compiler, on an architecture, on plugins, on other attributes...)
   * should be defined elsewhere (e.g. compiler_types.h or compiler-*.h).
   * The intention is to keep this file as simple as possible, as well as
   * compiler- and version-agnostic (e.g. avoiding GCC_VERSION checks).
   *
   * This file is meant to be sorted (by actual attribute name,
   * not by #define identifier). Use the __attribute__((__name__)) syntax
   * (i.e. with underscores) to avoid future collisions with other macros.
   * Provide links to the documentation of each supported compiler, if it exists.
   */
  
  /*
   * __has_attribute is supported on gcc >= 5, clang >= 2.9 and icc >= 17.
   * In the meantime, to support 4.6 <= gcc < 5, we implement __has_attribute
   * by hand.
   *
   * sparse does not support __has_attribute (yet) and defines __GNUC_MINOR__
   * depending on the compiler used to build it; however, these attributes have
   * no semantic effects for sparse, so it does not matter. Also note that,
   * in order to avoid sparse's warnings, even the unsupported ones must be
   * defined to 0.
   */
  #ifndef __has_attribute
  # define __has_attribute(x) __GCC4_has_attribute_##x
  # define __GCC4_has_attribute___assume_aligned__      (__GNUC_MINOR__ >= 9)
  # define __GCC4_has_attribute___copy__                0
  # define __GCC4_has_attribute___designated_init__     0
  # define __GCC4_has_attribute___externally_visible__  1
  # define __GCC4_has_attribute___noclone__             1
  # define __GCC4_has_attribute___nonstring__           0
  # define __GCC4_has_attribute___no_sanitize_address__ (__GNUC_MINOR__ >= 8)
  # define __GCC4_has_attribute___fallthrough__         0
  #endif
  
  /*
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-alias-function-attribute
   */
  #define __alias(symbol)                 __attribute__((__alias__(#symbol)))
  
  /*
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-aligned-function-attribute
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-aligned-type-attribute
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-aligned-variable-attribute
   */
  #define __aligned(x)                    __attribute__((__aligned__(x)))
  #define __aligned_largest               __attribute__((__aligned__))
  
  /*
   * Note: users of __always_inline currently do not write "inline" themselves,
   * which seems to be required by gcc to apply the attribute according
   * to its docs (and also "warning: always_inline function might not be
   * inlinable [-Wattributes]" is emitted).
   *
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-always_005finline-function-attribute
   * clang: mentioned
   */
  #define __always_inline                 inline __attribute__((__always_inline__))
  
  /*
   * The second argument is optional (default 0), so we use a variadic macro
   * to make the shorthand.
   *
   * Beware: Do not apply this to functions which may return
   * ERR_PTRs. Also, it is probably unwise to apply it to functions
   * returning extra information in the low bits (but in that case the
   * compiler should see some alignment anyway, when the return value is
   * massaged by 'flags = ptr & 3; ptr &= ~3;').
   *
   * Optional: only supported since gcc >= 4.9
   * Optional: not supported by icc
   *
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-assume_005faligned-function-attribute
   * clang: https://clang.llvm.org/docs/AttributeReference.html#assume-aligned
   */
  #if __has_attribute(__assume_aligned__)
  # define __assume_aligned(a, ...)       __attribute__((__assume_aligned__(a, ## __VA_ARGS__)))
  #else
  # define __assume_aligned(a, ...)
  #endif
  
  /*
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-cold-function-attribute
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Label-Attributes.html#index-cold-label-attribute
   */
  #define __cold                          __attribute__((__cold__))
  
  /*
   * Note the long name.
   *
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-const-function-attribute
   */
  #define __attribute_const__             __attribute__((__const__))
  
  /*
   * Optional: only supported since gcc >= 9
   * Optional: not supported by clang
   * Optional: not supported by icc
   *
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-copy-function-attribute
   */
  #if __has_attribute(__copy__)
  # define __copy(symbol)                 __attribute__((__copy__(symbol)))
  #else
  # define __copy(symbol)
  #endif
  
  /*
   * Don't. Just don't. See commit 771c035372a0 ("deprecate the '__deprecated'
   * attribute warnings entirely and for good") for more information.
   *
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-deprecated-function-attribute
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-deprecated-type-attribute
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-deprecated-variable-attribute
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Enumerator-Attributes.html#index-deprecated-enumerator-attribute
   * clang: https://clang.llvm.org/docs/AttributeReference.html#deprecated
   */
  #define __deprecated
  
  /*
   * Optional: only supported since gcc >= 5.1
   * Optional: not supported by clang
   * Optional: not supported by icc
   *
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-designated_005finit-type-attribute
   */
  #if __has_attribute(__designated_init__)
  # define __designated_init              __attribute__((__designated_init__))
  #else
  # define __designated_init
  #endif
  
  /*
   * Optional: not supported by clang
   *
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-externally_005fvisible-function-attribute
   */
  #if __has_attribute(__externally_visible__)
  # define __visible                      __attribute__((__externally_visible__))
  #else
  # define __visible
  #endif
  
  /*
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-format-function-attribute
   * clang: https://clang.llvm.org/docs/AttributeReference.html#format
   */
  #define __printf(a, b)                  __attribute__((__format__(printf, a, b)))
  #define __scanf(a, b)                   __attribute__((__format__(scanf, a, b)))
  
  /*
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-gnu_005finline-function-attribute
   * clang: https://clang.llvm.org/docs/AttributeReference.html#gnu-inline
   */
  #define __gnu_inline                    __attribute__((__gnu_inline__))
  
  /*
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-malloc-function-attribute
   */
  #define __malloc                        __attribute__((__malloc__))
  
  /*
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-mode-type-attribute
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-mode-variable-attribute
   */
  #define __mode(x)                       __attribute__((__mode__(x)))
  
  /*
   * Optional: not supported by clang
   *
   *  gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noclone-function-attribute
   */
  #if __has_attribute(__noclone__)
  # define __noclone                      __attribute__((__noclone__))
  #else
  # define __noclone
  #endif
  
  /*
   * Add the pseudo keyword 'fallthrough' so case statement blocks
   * must end with any of these keywords:
   *   break;
   *   fallthrough;
   *   goto <label>;
   *   return [expression];
   *
   *  gcc: https://gcc.gnu.org/onlinedocs/gcc/Statement-Attributes.html#Statement-Attributes
   */
  #if __has_attribute(__fallthrough__)
  # define fallthrough                    __attribute__((__fallthrough__))
  #else
  # define fallthrough                    do {} while (0)  /* fallthrough */
  #endif
  
  /*
   * Note the missing underscores.
   *
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noinline-function-attribute
   * clang: mentioned
   */
  #define   noinline                      __attribute__((__noinline__))
  
  /*
   * Optional: only supported since gcc >= 8
   * Optional: not supported by clang
   * Optional: not supported by icc
   *
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-nonstring-variable-attribute
   */
  #if __has_attribute(__nonstring__)
  # define __nonstring                    __attribute__((__nonstring__))
  #else
  # define __nonstring
  #endif
  
  /*
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noreturn-function-attribute
   * clang: https://clang.llvm.org/docs/AttributeReference.html#noreturn
   * clang: https://clang.llvm.org/docs/AttributeReference.html#id1
   */
  #define __noreturn                      __attribute__((__noreturn__))
  
  /*
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-packed-type-attribute
   * clang: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-packed-variable-attribute
   */
  #define __packed                        __attribute__((__packed__))
  
  /*
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-pure-function-attribute
   */
  #define __pure                          __attribute__((__pure__))
  
  /*
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-section-function-attribute
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-section-variable-attribute
   * clang: https://clang.llvm.org/docs/AttributeReference.html#section-declspec-allocate
   */
  #define __section(S)                    __attribute__((__section__(#S)))
  
  /*
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-unused-function-attribute
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-unused-type-attribute
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-unused-variable-attribute
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Label-Attributes.html#index-unused-label-attribute
   * clang: https://clang.llvm.org/docs/AttributeReference.html#maybe-unused-unused
   */
  #define __always_unused                 __attribute__((__unused__))
  #define __maybe_unused                  __attribute__((__unused__))
  
  /*
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-used-function-attribute
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-used-variable-attribute
   */
  #define __used                          __attribute__((__used__))
  
  /*
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-weak-function-attribute
   *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-weak-variable-attribute
   */
  #define __weak                          __attribute__((__weak__))
  
  #endif /* __LINUX_COMPILER_ATTRIBUTES_H */
  